The present invention is directed to a novel combination of an appliance with a frozen food that is topped by dough to allow foodstuffs which must be heated, baked and browned to be processed by a microwave oven without undercooking of the interior food substance and deterioration of the crust into an unappealing, unappetizing heated mass of soggy dough. Heretofore this major problem has been unsolved so that pot pies and, indeed, fruit pies have not generally been available in a frozen condition and yet capable of being reconstituted in a microwave oven in a fashion to produce an appetizing end result. For that reason, pot pies and other frozen pies topped with a dough from quality producers have been packaged and sold in a metal pan which is to be placed into a conventional convection oven. Only in this way was it possible to obtain the desired appearance and taste. This convection cooking requires a substantially long heating time to reconstitute the frozen pie into an acceptable food entree or dessert. With the advent of microwave cooking of frozen foodstuffs and general availability of such ovens, microwave cooking has become overwhelmingly demanded by the consuming public. Consequently, manufacturers of quality pot pies and other crusted food items, or foodstuff, have been seeking an acceptable vehicle for manufacturing frozen pies, transporting them in an inexpensive carton for display at a retail outlet and then for reconstitution by microwave oven in a cooking time drastically less than the time required for baking the pie in a conventional convection oven. So far, these efforts to produce a microwave heatable pot pie in an inexpensive transporting arrangement have generally alluded the manufacturers of pot pies. As an attempt to overcome this problem, some pies have been prebaked so that the crust is browned and then sold in a plastic container which can be heated in a microwave oven. This is nothing more than warming or reheating a previously cooked pie and does not solve the problem and produce the end result of an uncooked pie being baked and browned by a microwave oven. In addition, prebaking or partial baking of the pie tends to cause separation of the crust during shipment and/or reconstitution. Some pies are made with the crust somewhat rigid and spaced from the internal filler food. Others have placed substances on the crust to disguise the failure to bring the crust to the desired cooked condition.
The various patents incorporated by reference herein illustrate the extent to which major manufacturers are attempting to utilize microwave ovens for reconstituting foodstuffs of various type which involve browning and other localized heating. None of these prior art patents, incorporated for background information, teach the novel combination of a pie and appliance in accordance with the present invention; however, certain aspects of these patents are relevant to the background of the invention and these various aspects will be described briefly to illustrate the futility of prior patented concepts in solving the basic problem to which the present invention is directed. This apparent futility is carried over into the marketplace where the problem of cooking pot pies has not been solved.
Brastad U.S. Pat. No. 4,230,924 relates to an early effort to develop a wrapper material to brown the surface of a foodstuff wrapped in the material and employs a concept of converting energy at the wrapping to brown or crispen the particular portion of the foodstuff against which the wrapping is held. The amount of heating is controlled by increasing non-metallic gaps or stripes between metallic islands. The particular technical phenomenon employed in heating the wrapping material is not explained; however, there is an attempt to indicate microwave heating of the wrapper by some conversion of the microwave energy to heat energy. This theory relates to an embodiment of the invention wherein a vacuum evaporation process is employed for depositing aluminum onto a plastic strip supported by a paperboard. This is the general type of material contemplated by the present invention; however, the material is a flexible wrapper and could not be employed in accordance with the present invention. There is no disclosure in this early patent of a pie receptacle using a microwave impervious receptacle for housing the food to be heated and controlling cooking of a pot pie or similar food item.
Bradstad U.S. Pat. No. 4,267,420 relates to a material similar to Brastad U.S. Pat. No. 4,230,924; however, this second patent does not explain the theory of how the aluminum vacuum deposited on the film generates heat at the surface, except for the use of a "myriad" of irregular contoured islands with dielectric channels extending therebetween. To control the amount of browning, the thickness of the metallized coating is apparently changed. This flexible material is employed for "wrapping" material to cook substances, such as fish sticks. The teaching of this patent is not more relevant than Brastad U.S. Pat. No. 4,230,924, except is seems to be more specific on the phenomenon employed in heating a thin metallized surface by microwave to produce heat at the metallized surface of the film. Otherwise it is not relevant to the present invention.
Keefer U.S. Pat. No. 4,656,325 is apparently directed to certain experimental work in Canada, which has resulted in development of a carton having a lower metal ground plane and an upper cover spaced a substantial distance above the foodstuff. This cover has a high dielectric constant and is produced by utilizing relatively large areas of metal material on the outside of the cover. The metal foil is on the outside of the cover and is employed to increase the effective dielectric constant of the cover. This concept is allegedly used to control reflection of microwaves. A relatively large spacing above the foodstuff, in the range of 0.8 to 2.0 cm, is required for the heating system of this patent. This patent includes the concept of a metal foil container in combination with a non-reflecting energy cover having a special design. The cover must be relatively thick or include islands of metal paint or foil. To accomplish the intent of the disclosed invention of this prior patent, metal is required at what is referred to as the ground plane only. Consequently, Keefer U.S. Pat. No. 4,656,325 relates only to a more efficient manner of heating foodstuff and is not directed toward the concept of browning an upper layer of dough as contemplated by the present invention.
Seiferth U.S. Pat. No. 4,641,005 apparently defines a commercially available susceptor material contemplated for use in the present invention as one component of the novel appliance. This Seiferth patent utilizes susceptor material to construct the carton or container itself. It is not used as a separate and distinct susceptor sheet over the crust material as contemplated in the present invention.
Brown U.S. Pat. No. 3,626,641 combines the material in Seiferth U.S. Pat. No. 4,641,005 with a carton to hold a layer of this material a fixed distance "a" above the crust of a pot pie. Again, spacing is indicated to be critical to produce radiant heating. This concept differs from the present invention wherein the material is laid directly on the crust so that the material creates substantially conductive heating as the crust expands and pushes the susceptor sheet upwardly. Since the same material, as used in the Seiferth patent is employed with the same theory in Brown U.S. Pat. No. 4,626,641, it is assumed that no microwave passes through the heating or crispening means of this patent to heat the inside of the pot pie as the crust is browned, an important feature of the present invention. For that reason, the insert of the Brown patent for holding the plastic pie container includes a lower opening to allow direct microwave heating of the pot pie filling which is not used in the novel appliance of the present invention. This feature of direct heating is completely different than the present invention wherein all heating of the filler is to be accomplished by microwave penetration of the crust to bake the crust for browning. This cooking concept is a feature of the present invention and is not taught by Brown U.S. Pat. No. 4,626,641. The spacing of the susceptor sheet is fixed by employing a carton; therefore, heating of the crust is uneven as the crust expands. This spacing variation is proportional to the square of distance above the crust. In accordance with the present invention, by placing the susceptor, as one element of the novel cooking appliance, directly on the crust, uniform conduction heating occurs as the crust rises due to baking by the penetrating microwave energy. Consequently, the appliance of the present invention heats the crust uniformly while the susceptor is being employed without constraint of a container or carton.
A spring biased susceptor sheet is taught in Maroszek U.S. Pat. No. 4,594,492. This patent relates to the use of a susceptor forced against the upper surface of a food in a carton or container to be heated by microwave. This patent also teaches the concept of partially shielding the foodstuff to limit the amount of microwave heating of material in the package itself. There is no suggestion of discarding the carton and using a single susceptor sheet resting upon the upper surface of the crust of a pot pie in a microwave impervious receptacle for the purposes of heating, baking and browning a pot pie.
At this time, there is no commercially available appliance for reconstituting frozen pot pies to the quality of convection cooking, even in view of the background patents pertinent ones which have been described above. There is a substantial need in the marketplace to produce a commercially acceptable, easily manipulable and inexpensive appliance which can be used for the reconstitution of a pot pie so that pot pies can be converted from convection oven reconstitution to microwave reconstitution without sacrificing quality.
Quality of the cooked product is extremely important to a manufacturer of frozen foods since marketing of a pot pie which does not have high quality after cooking will adversely affect the reputation of the manufacturer for its total product line. Consequently, only a sure, repeatable process is acceptable in the mass marketing field and any minor change to give the needed quality is critical.